Extension Block Pinning versus percutaneous Fragment Reduction with a Towel Clip and extension Block Pinning with direct Pin Fixation for Treatment of Mallet Fracture.

Abstract

This study compared the clinical and radiographic results between extension block pinning (Group A) and percutaneous reduction of the dorsal fragment with a towel clip followed by extension block pinning with direct pin fixation (Group B) for the treatment of mallet fractures. A total of 69 patients (group A = 34 patients, group B = 35 patients) who underwent operative treatment for mallet fractures from June 2008 to November 2017 with ≥ 6 months post-surgical follow-up were analysed retrospectively. The extent of subluxation of the distal interphalangeal joint, articular involvement of fracture fragment, fracture gap, and articular step-off were examined on plain radiographs before and after surgery. The functional outcomes were evaluated with the Crawford rating system. The postoperative step-offs were 0.16 mm in group A and 0.01 mm in group B. Group B had a significantly better anatomical outcome than group A. Five patients in group A had a loss of reduction. Among them, two had malunion and post-traumatic arthritis. Meanwhile, no patients in group B presented with loss of reduction and nonunion. The mean extension lags were 4.2° in group A and 1.6° in group B. However, functional outcome did not differ between the two groups at the final follow-up. Fracture reduction using a towel clip and extension block pinning with direct pin insertion for mallet fracture facilitated the anatomical reduction of fragments, and allowed for stable fixation of fragments. Compared with extension block pinning technique, this technique has shown better anatomical results and stability, but not better clinical results.